For hams who want more in-depth information about APRS, see Bob Bruninga’s APRS site. This provides more information about the full spectrum of APRS communication.http://www.aprs.org/

In SAR applications, what equipment do I need to get on the air?

Tracker: (the transmitter unit that goes in field pack)

You must be a licensed ham radio operator (technician or higher license class) or there must be a license ham acting as a “control operator” for all stations transmitting over the ham bands. FCC requirement.

A reliable GPS that works in dense foliage capable of transmitting an NMEA text string to an RS-232 connector (DB9).

A reliable handheld 2 meter radio (144.390Mz) capable of transmitting 1 to 3W for the duration of a search. Hiigh capacity battery packs are strongly recommended.

Exact call signs of the units to be tracked (including the suffix –n designator)

(Note: Transmitting stations must be in range of a digipeater which is tied to the Internet via IGates. In most urban areas of the Bay Area, this is not a problem. When you get into the remote area along the Pacific Coast or Sierra mountains, you may encounter limitations.)

If I want to monitor station packets directly, what do I need? (e.g. when you don’t have access to the web in the field)?

APRS Receive Station: (the receiving unit which maps the position reports on a computer)

You do not need to be a ham radio operator just to receive radio transmissions. Be sure the radio is locked not to transmit or the software is set up so the unit is not digipeating.

A Terminal Node Controller (TNC)

A reliable receive radio that can interface with a TNC – portable or mobile

Good external antenna capable of picking up weak radio signals in the field

Most SAR teams are using either DMapper or WinAPRS on the Microsoft Windows platform, although WinAPRS is available for the Mac. These packages seem to be well suited for use of topographical maps. APRS Point and APRS + SA are more geared toward tracking of vehicles over a larger area. Map details are not available at the same level as the recommended programs.

What can I do to increases reliability in the field?

On average, APRS is about 70% reliable. The key factors that can increase reliability and usability are:

Good antennas and power (on both receive and tracker stations)

Rugged tracker units that can handle the elements

Extra batteries for radio and tracker

Setting up digipeating station on a high mountain top above the search area

Competent and experienced APRS users who have years of field experience in deploying and operating APRS

Dedicated computer for tracking and mapping

Where do I go to get help?

APRS for SAR applications is very much experimental. Everyone has an opinion and there are 1000 ways to make a tracker. Some folks swear by certain software programs; there functions in every software package that users hate. It all comes down to what the user is most comfortable with both with Trackers and Software.

APRS for SAR is a special application, and the challenges of poor reception, extreme environment, and an emergency situation tend to favor systems which are tested, reliable, and easy to use. Folks who have actual field experience in deploying and using APRS for searches are the ones to seek out.

Feel free to contact any of the following for assistance. This list will grow as more teams gain experience with APRS.